diff --git a/notebooks/notebook_compare_one_day_data.ipynb b/notebooks/notebook_compare_one_day_data.ipynb
index 657b63d..f52e91e 100644
--- a/notebooks/notebook_compare_one_day_data.ipynb
+++ b/notebooks/notebook_compare_one_day_data.ipynb
@@ -137,6 +137,11 @@
     "# User input the city, for the weather\n",
     "city_2 = input_place()\n",
     "\n",
+    "# Cheks that the two cities is not the same\n",
+    "while city_2.lower() == city_1.lower():\n",
+    "    print(\"The two places must be different\")\n",
+    "    city_2 = input_place()\n",
+    "\n",
     "# Start_date is the first timestamp, end_date is the last\n",
     "start_date, end_date = timestamps[0], timestamps[-1]\n",
     "\n",
diff --git a/notebooks/notebook_compare_one_week_data.ipynb b/notebooks/notebook_compare_one_week_data.ipynb
index f1a9a6d..34a6aa4 100644
--- a/notebooks/notebook_compare_one_week_data.ipynb
+++ b/notebooks/notebook_compare_one_week_data.ipynb
@@ -131,6 +131,11 @@
     "# User input the city, for the weather\n",
     "city_2 = input_place()\n",
     "\n",
+    "# Cheks that the two cities is not the same\n",
+    "while city_2.lower() == city_1.lower():\n",
+    "    print(\"The two places must be different\")\n",
+    "    city_2 = input_place()\n",
+    "\n",
     "# Stores the values in the variables\n",
     "data_city_2, folder = fetch_time_data(unix_start_date, unix_end_date, city_2)"
    ]
diff --git a/notebooks/notebook_compare_statistic_data.ipynb b/notebooks/notebook_compare_statistic_data.ipynb
index 77afeb1..9821391 100644
--- a/notebooks/notebook_compare_statistic_data.ipynb
+++ b/notebooks/notebook_compare_statistic_data.ipynb
@@ -81,6 +81,11 @@
     "# User input the city, for the weather\n",
     "city_2 = input_place()\n",
     "\n",
+    "# Cheks that the two cities is not the same\n",
+    "while city_2.lower() == city_1.lower():\n",
+    "    print(\"The two places must be different\")\n",
+    "    city_2 = input_place()\n",
+    "\n",
     "data_city_2, folder = fetch_stat_data(city_2)"
    ]
   },